Method and apparatus for treating boxboard blanks



June 25, 1957 D. KIRK 2,797,096

METHOD AND APPARATUS FOR TREATING BOXBOARD BLANKS Filed July 50, 1953 4 Sheets-Sheet 1 FIG. I

INVEN TOR. DOUGLAS KIRK v ATTYS.

June 25, 1957 K R 2,797,096

METHOD AND APPARATUS FOR TREATING B'OXBOARD BLANKS Filed JulyEO, 1.95s 4 Sheets-Sheet 2 l l I I i I INVENTOR.

ATT YS D. KIRK June 25, 19 57 METHOD AND APPARATUS FOR TREATING BOXBOARD BLANKS Filed July 50, 1955 4 Sheets-Sheet 5 ATTYS m OE INVENTOR. DOUGLAS KIRK June 25; 1957 KlRK 2,797,096

METHOD AND APPARATUS OR TREATING BOXBOARD BLANKS Filed July 30, 1953 4 Sheets-Sheet 4 Q INVENTOR. DOUGLAS KIRK ATTYS METHOD AND APPARATUS FOR TREATING BOXBOARD BLANKS .Douglas Kirk, Hudson, Ohio, assignor to The Quaker Oats Company, Chicago, 11]., a corporation of New Jersey The present invention relates to the manufacture of boxes, cartons or containers made of a relatively light stock such as strawboard, cardboard or fiberboard. The invention was developed with respect to the manufacture of boxes for cereals, flours, and the like, but is not limited to that field.

The stock from which boxes of the type set forth are made may be of varied thickness or weight, for example that for which the invention was developed is a fiberboard of approximately .021" thickness. This stock is ordinarily received by the manufacturer of the boxes in large rolls containing several thousands of feet of the stock. This roll is mounted at the intake end of a machine which cuts out, scores and notches the blanks, which are then transferred to the box-making machinery. These blanking machines operate very rapidly and are capable of passing 1200 feet of the stock in one minute.

As the stock is fed to the blanking machine from a roll, the blanks, when delivered by the machine, have a curvature or arch in the direction in which the stock was rolled on the supply roll. This arch or curvature in the blanks is objectionable when the blanks are transferred to the box-forming machines and unless the blanks are flattened out the operation of the box-forming machine will be seriously impaired and much waste will be created.

Several expedients have been used to take the curvature out of the blanks, one of the commoner methods being to insert a straightening roller in the line of the stock feed which will operate upon the web before it reaches the cutting knives and cause the web to travel in an are which is the reverse of the are on the roll of stock. This expedient has the serious objection that it tends to crack the stock and make many blanks which have to be rejected. This method is particularly objectionable in machines which operate at very high speeds because the travel of the web over the straightening roller places a severe tension on the rapidly moving stock and will cause frequent breaks in the web.

The method and apparatus of the present invention operates upon the blanks after they are cut, to place a reverse curvature in the blanks, and in order to avoid cracking the blanks by straightening them out one at a time, the machine operates upon many blanks at the same time so that the strain is not placed upon a single thickness of stock.

The machine and method shown in this application have been put into actual production and have operated to remove the objectionable curvature from blanks of stock without cracking or breaking the blanks and without making it necessary to slow down the blank-making machine.

The apparatus for accomplishing the results set forth is shown in connection with and as a part of the web blanking machine, because this is where the improvement is most advantageously applied. However, the invention is not limited to the type of machine shown. The invention is shown in its best known and preferred form, but

changes, modifications and improvements may be made atent ice therein without sacrificing any of the beneficial results flowing from the invention. The type of blank shown herein is by way of example only.

In the drawings,

Fig. 1 is a side elevation of a standard blanking machine for operating on a web of stock, with the improved mechanism shown at the right or delivery end of the machine.

Fig. 2 is a plan view of the improved straightening mechanism.

Fig. 3 is aside elevation of the parts shown in Fig. 2.

Fig. 4 is an enlarged view taken at the straightening roller on the line 44 of Fig. 2.

Fig. 5 is a perspective view of a single blank.

It will be understood that because of the limitations imposed upon the making of drawings, the number of blanks shown passing at one time through the straightening process is greatly reduced. show more than about ten thicknesses or plies of material passing through the straightening rolls at one time, Whereas, at least twice that number of blanks pass through the straightening process at one time.

The main blanking machine is indicated as a whole at 1. It contains a plurality of cutting, scoring and notching rolls which are standard in design and construction, and need not be described in detail. The stock which is of the type described is mounted in the supply roll 2 and is fed into the machine and propelled through the machine by power applied to the rolls. The blanks, one of which is shown at 4 in Fig. 5 are scored at 401, notched at 419, and slit at 40 ready for the box-making machine, and are then delivered to short belts 6.

The belts 6 are driven from the main machine through the power reduction drive indicated at 7 at a much slower speed than the travel of the web through the cutting and scoring rolls, so that the blanks are pilled up, shingle fashion, on the belts 6, as is attempted to be shown in Figs. 3 and 4. The belts 6 are V-belts which are trained over pulleys 8 at the delivery end and pulleys 9 on shaft 11 at the intake end, driven by the power drive 7. Pulleys 8 are mounted on the shaft 10 to which are attached the belt tighteners 12 mounted in brackets 14 carried by the supplemental frame work 15 which supports the straightening mechanism.

In actual installations the web has been run through the blanking machine at as high as 1200 feet per minute, while the bolts 6 run at approximately 50 feet per minute, which causes the blanks to pile up to a thickness of 2() or 21 plies or layers at any point.

From the belts 6 the stream of piled up blanks passes to a second pair of V-belts 20 trained over pulleys 21 attached to the shaft 10 and over pulleys 22 fixed to a shaft 23 which is rotatable in a pair of uprights 24 attached to the frame 15. A supplemental supporting roller 25 is located between the pulleys 22 which prevents the blanks from bowing transversely.

As is shown clearly in Figs. 3 and 4, the upper run of the belts 20 is deflected into a sharp dip or are which is the reverse in curvature with respect to the curvature of the web of stock on the supply roll 2. This is done by passing the belts 20 over idler pulleys 28 mounted on a shaft 29 located between the pulleys 21 and the pulleys 22. The portion of the stream of over-lapping blanks that is located between pulleys 22 and28 shall be known as the span. Midway of the pulleys 22 and 28 and above the belts 20 is located the roller 30 which is fixed to the shaft 32 adjustably mounted in sliding bearings 35 movable in vertical ways 36 formed in the brackets 24 and held by the shafts 38, threaded in the cross plates 7 39 across the top of the brackets 24. The roller 30 may be adjusted to exert more or less of an acute bend in the belts 20 and consequently more or less bending of It was not possible tothe blanks 4 as they pass beneath the roll 30. The roll is preferably covered with rubber or a yielding material about the same degree of softness as the ordinary wringer roller.

In order to move the many blanks through the depression at the straightening roller 30, without having the blanks slide upon one another, it is necessary to drive the roller 30 at the same surface speed as the speed of the belts 20. For this purpose the shaft 32 is provided with a sprocket 42 which is in mesh with a chain 43. The

chain 43 passes over the idler sprocket 44 and around the idler sprocket 45 at either side of the sprocket 42, these sprockets being adjustably mounted on the lower ends of plates 46 and 47, respectively.. Each plate is slotted and is held in place on the bracket 24 by bolts 48. The chain 43 is driven by any suitable means preferably by the drive shaft 11.

It will be seen that passing the blanks in many plies over the dip in the belts 20 and under and around the roller 30 causes a curvature or bend to be imparted to the blanks which offsets and corrects the curvature placed in the stock by the fact that it was wound on the supply roll 2. The important point is that this bending action in the reverse curvature is given to many blanks at the same time so that no single blank takes the effect of the bending force. In this way the blanks are effectively straightened out, but no blank is split or cracked, as it would be had it taken the reverse bending without the support of many other blanks with which it is associated at the time.

The blanks, now freed of any curvature or arching, are delivered to the take-off belt 52 on which they fall as they pass over the pulleys 22 and roller 25. The receiving end of the belt 52 passes around a pulley 54 fixed to shaft 55 mounted in the end of the frame 56 that is supported by brackets 57 rising from the frame 15. A sprocket 60 on shaft 55, which is driven by the chain 61, drives the belt 52. Chain 61 is driven through sprocket 63 on shaft 64 and sprocket 65 and chain 66 from the shaft 11 of the pulleys 9. Arms 68 mounted on the frame 56 bridge the gap between the belts 20 and the belt 52.

It will be seen that a new and satisfactory method has been devised and perfected for removing the heretofore troublesome arch or curvature from blanks such as shown and described. This has been done without requiring the blanking machine to be slowed down; indeed, with the mechanism shown these blanking machines may be run at speeds not heretofore considered practical. The operation is done without cracking the blanks and thus much waste is avoided.

The belts 20 are adjusted so that when idle they will contact the straightening roller 30, but due to the fact that they are V-belts with some inherent elasticity, they will give sufliciently to pass the stack through the dip and will hold the layers firmly together against the roller 30.

The details of the machine as set forth herein need not be followed in order to realize the invention, but changes and modifications may be incorporated in the-machine, as will be evident to those familiar with this art. The general term fiberboard is used in the claims-to designate the stock. It has been found that with certain types of stock 20 to 21 plies passing through the bending operation will give excellent results but it is apparent that with different gauges of stock, the number will be increased or diminished depending upon the various factors present.

What is claimed is:

1. A method of flattening cut fiberboard blanks having a pronounced curvaturein one direction comprising the steps of, forming a moving packin which said blanks are superposed in a plurality of layers and in shingle fashion, yieldably supporting a moving span of said pack, the leading end of said span being higher than the'trailing end, and exerting a bending force upon the central portion of said span while in motion and in the direction opposite to said pronounced curvature.

2. A method of flattening cut fiberboard blanks having a pronounced curvature in one direction comprising the steps of, forming a moving continuous pack in which said blanks are superposed in a plurality of layers and in shingle fashion, yieldably supporting a moving span of said pack, the leading end of said span being higher than the trailing end, continuously applying a downward bending pressure to the central portion of said span to cause said portion to bend in the direction opposite to said pronounced curvature, and continuously causing said pack 7 to be stacked with said blanks in a substantially vertical position.

3. A method of flattening cut fiberboard blanks having a pronounced curve in one direction comprising the steps of: forming a moving continuous pack in which said blanks are superposed in a plurality of layers and in shingle fashion, said pack having a thickness at least 20 times greater than that of an individual blank; yieldably supporting a moving span of said pack upon two rollable surfaces, the second of said surfaces being higher than the first; continuously exerting a bending force upon the central portion of said span while in motion and in the direction opposite to said pronounced curvature; and continuously causing said pack to be stacked with said blanks in a substantially vertical position.

4. In combination with a mechanism delivering cut blanks of fiberboard having a pronounced curvature in one direction, apparatus for flattening said blanks comprising: conveyor means receiving said delivered blanks and forming a moving pack thereof in which said blanks are superposed in a plurality of layers and in shingle fashion; a resilient conveyor means receiving said pack from said first conveyor means; a pair of rollable surfaces spaced apart along said resilient conveyor means for contacting a portion thereof, the second of said surfaces being higher than the first; and pressure means between said rollable surfaces and above said resilient conveyor means adapted to exert a bending force in the direction opposite to said pronounced curvature upon a span of said pack while in motion between said surfaces.

5. In combination with a mechanism delivering cut blanks of fiberboard having a pronounced curvature in one direction, apparatus for flattening said blanks comprising: conveyor means receiving said delivered blanks and forming a moving pack thereof in which said blanks are superposed in a plurality of layers and in shingle fashion, said pack having a thickness substantially greater than that of an individual blank; a resilient conveyor means receiving said pack from said first conveyor means; a pair of rollers spaced apart along said resilient conveyor means for contacting a portion thereof, the second of said rollers having its peripheral surface higher than the first; pressure means between said rollers and above said resilient conveyor means adapted to continuously apply a downward bending pressure against the central portion of a span of said pack while in motion upon said resilient conveyor means; and means for continuously stacking said pack with said blanks in a substantially vertical position.

6. In combination with a mechanism delivering cut blanks of fiberboard having a pronounced curvature in an upward direction, apparatus for flattening said blanks comprising: a conveyor belt receiving said delivered blanks and moving at a rate substantially less than the delivery rate of said blanks so as to form a continuous pack thereof in which the blanks are superposed in at least 20 layers and in shingle fashion; an endless resilient belt receiving said pack, moving at approximately the same rate as said conveyor belt, and revolving around a pair of rollers, said rollers being a larger diameter intake roller and a smaller diameter discharge roller; an idler roller located between said intake and discharge rollers within the loop of said belt, said idler roller having an axis of rotation below and a diameter substantially the same as that of said discharge roller; and pressure means located between said idler and discharge rollers and above said resilient belt to continuously apply a downward bending pressure against the central portion of a span of said pack while in motion upon said resilient belt.

7. In combination with a mechanism delivering cut blanks of fiberboard having a pronounced curvature in an upward direction, apparatus for flattening said blanks comprising: a conveyor belt receiving said delivered blanks and moving at a rate substantially less than the delivery rate of said blanks so as to form a continuous pack thereof in which the blanks are superposed in at least 20 layers and in shingle fashion; an endless resilient belt receiving said pack, moving at approximately the same rate as said conveyor belt, and revolving around a pair of rollers, said rollers being a larger diameter intake roller and a smaller diameter discharge roller; an idle roller located between said intake and discharge rollers within the loop of said belt, said idler roller having an axis of rotation below and a diameter substantially the same as that of said discharge roller; a pressure roller located between said idler and discharge rollers and above said resilient belt to continuously apply a downward bending pressure against the central portion of a span of said pack while in motion upon said resilient belt, and means for continuously stacking said pack with said blanks in a substantially vertical position. 

